Witherspoon, 34, has not commented on the report by Us Weekly magazine, which said she will wear a Monique Lhuillier design and marry Toth, a 40-year-old talent agent, in a field near her ranch in Ojai, California.
The two have been dating for about a year. This will mark the second marriage for the actress, who was married to actor Ryan Phillippe, 36, between 1999 and 2008. The two are parents to daughter Ava, 11 and son Deacon, 7.
Witherspoon and Toth were first linked together in January, not long after she and actor Jake Gyllenhaal confirmed they had broken up after dating for about three years.
Witherspoon and Toth fended off engagement rumors in October.
She is known for movies such as 'Legally Blonde' and won an Oscar for the 2005 film 'Walk the Line'.
